JavaScript实现穷举排列（permutation）算法谜题解答

谜题

穷举一个数组中各个元素的排列

策略

减而治之、递归

JavaScript解

复制代码代码如下:
/**
* Created by cshao on 12/23/14.
*/
function getPermutation（arr） {
if （arr.length == 1） {
    return [arr];
}
var permutation = [];
for （var i=0; i<arr.length; i++） {
    var firstEle = arr[i];
    var arrClone = arr.slice（0）;
    arrClone.splice（i, 1）;
    var childPermutation = getPermutation（arrClone）;
    for （var j=0; j<childPermutation.length; j++） {
      childPermutation[j].unshift（firstEle）;
    }
    permutation = permutation.concat（childPermutation）;
}
return permutation;
}
var permutation = getPermutation（["a","b","c"]）;
console.dir（permutation）;

结果

复制代码代码如下:
[ [ "a", "b", "c" ],
[ "a", "c", "b" ],
[ "b", "a", "c" ],
[ "b", "c", "a" ],
[ "c", "a", "b" ],
[ "c", "b", "a" ] ]